Alarm clock



y 3, 1967 B. KLEINERMAN 3,320,739

ALARM CLOCK Filed May 13 1965 2 Sheets-Sheet l A as May 23, 1967 B.KLEINERMAN ALARM CLOCK 2 Sheets-Sheet 2 Filed May 13, 1965 United StatesPatent 3,320,739 ALARM CLOCK Ben Kleinerman, New Hyde Park, N.Y.,assignor to Jerry G. Bechhofer, New York, N.Y. Filed May 13, 1965, Ser.No. 455,434 7 Claims. (ill. 58-38) This invention relates to alarmclocks. One of the first reactions of sleepers, on hearing the buzzer ofan alarm clock, is to grope drowsily for the clock to shut it off. Thisis, for many, a wearing, unpleasant and strenuous procedure,particularly if the person has just been roused from a deep sleep.

It is an object of this invention to simplify the operation of shuttingoff the alarm.

Another object of this invention is to provide an alarm clock whosealarm may be shut off merely by the approach of the hand of thehalf-awakened person, without touching the clock.

Other objects of this invention will be apparent from the followingdetailed description and claims.

In accordance With one aspect of this invention, an alarm clock having atime-controlled alarm is provided with alarm-inactivating meansresponsive to changes in the electromagnetic field around the clockresulting from the approach of the human hand to a zone near the clock.In a preferred form, the device is responsive to the body capacitance ofthe user and includes normally passive means responsive to activatingsignals'and a capacitively effective element cooperable with bodycapacitance for coupling the activating signals to the normally passivemeans to cause the alarm to be shut oil. The normally passive means, ina preferred construction, is responsive to low frequency and has atrigger electrode which, when coupled by the body capacitance to thesignal generated by adjacent AC. power wires, permits analarm-deactivating current to pass through the normally passive means.The trigger electrode may be part of a device such as a thyratron, asilicon-controlled rectifier, a flip-flop or the like; such a device mayform part of -a circuit containing also a solenoid operable to shut offthe alarm. Ordinarily no current can flow through this circuit, but whenbody capacitance is brought into proximity to the capacitive elementwhich is connected to the trigger electrode, the thyratron, siliconcontrolled rectifier or similar device fires, permitting current to flowand thus operating the solenoid. The trigger electrode is advantageouslypreset at a bias greatly exceeding the level at which the device Willfire with the normal energization of its output circuit; this minimizesthe effect of transients in the power supply.

One form of the invention is illustrated in the accompanying drawing inwhich:

FIGURE 1 is a front view of a clock;

FIGURE 2 is a rear view of the clock;

FIGURE 3 is a schematic view of a portion of the alarm mechanism;

FIGURE 4 is a view like that of FIG. 3, showing the position of theparts during the operation of an alarm repeat cycle;

FIGURE 5 is a schematic view of another portion of the alarm mechanism;and

FIGURE 6 is a circuit diagram of an embodiment of this invention.

In one preferred form, the device of this invention is produced bymodifying an electric alarm clock 11 of the usual type having aninsulating plastic housing 12, a face 13 and hands 14 driven by a motor16 operating on 60 c.p.s. alternating current supplied through leads 17and 18 connected to the corresponding prongs 20, 19, of a plug 22fitting in a household electrical receptacle 23.

As is conventional, the magnetic field of the motor 16 is created by awinding 24 around a laminated field core 26 which also acts to actuatean alarm buzzer hammer 27 when the alarm is to be sounded. The hammer 27is resiliently urged toward the adjacent portion 28 of the core, but isnormally maintained in an inoperative position, a short distance awayfrom portion 28 until the preset time for sounding the alarm buzzer isreached. When this preset time is reached the hammer is permitted tomove rapidly toward the core.

More particularly, the hammer 27 is mounted near the head end of aresilient lever 29, of leaf spring material rigidly supported at itstail end 31. The hammer is normally maintained in its inactive positionby a pivoted pusher element 32 (FIG. 5) which presses upwardly againstthe lever 29 near its head end so as to bend that lever upwardly againstthe force of its leaf spring material. The pusher element 32 is itselfmaintained in its alarm-inactivating position by the conventional alarmclockwork (indicated generally as 34, FIG. 5), which comprises an alarmcam 36 mounted on a clockworkdri-ven gear 37 and having a tip 38 whichengages one face of a coaxially mounted wheel 39 having an aperture 41and carrying, on its other face, a pin 42 which presses against thepusher element 32. At the preset time the rotation of the gear 37 bringsthe tip 38 of the alarm cam 36 opposite the aperture 41 of the wheel 39,permitting the wheel to approach the gear, and thus releasing the lever29 so that the hammer may move, under the resilient force in the levertoward the core 26 to sound the alarm. Unless shut off manually, thealarm continues to sound for a relatively long period of time untilfurther rotation of the gear 37 and corresponding movement of the cam 36causes the wheel 39 to be pushed by the alarm cam a sufiicient distancefrom the gear so that the hammer is forced (by the effect of themovements of pin 42 and pusher element 32) to an inoperative position attheclose of the alarm period.

The alarm may be shut off manually by the usual reset rod 43, which hasa cam portion engaging the lever 29 so as to lift the hammer 27 awayfrom the core 26 when the reset rod is pushed in by the user. Usuallythe reset rod is accessible to manual operation from the back of theclock.

It is also common for alarm clocks to have an alarm repeat controlmechanism actuated by an easily accessible push button 44 (FIG. 1) atthe top of the clock.

This feature makes it possible for the awakened sleeper to shut off thealarm without immediately making the onerous effort of moving the resetrod 43. If after the predetermined alarm-repeat time (say, 5 minutes)the reset rod still has not been operated manually, the alarmrepeatcontrol device permits the alarm to sound again, and so on, until thefurther rotation of the gear 37 by the clockwork inactivates the hammer27. More particularly, the alarm-repeat control mechanism includes atime-controlled latching device 45 (FIGS. 3 and 4) and a lifter element46, pivoted at 47. Tapping of the push button 44, against the force ofits spring 48, moves the lifter element 46, which engages lever 29 toraise the hammer 27 away from the core 26. The latching device 45 thenretains the lifter element in its lever-lifting position for thepredetermined alarm-repeat period. There is an operative connectionbetween the latching device 45 and the clockwork which gradually drivesthe latching device from the position shown in FIG. 4 to the positionshown in FIG. 3 by the end of the predetermined alarm-repeat time,causing the alarm to sound again. More particularly, the latching device45 comprises an arcuate toothed element 49 pivoted at one end 51 to thelifter element 46 and engaged at its other end 52 by a spring 53 whichserves to press the toothed lower portion 54 against the teeth of a gear56 of the clockwork of the alarm clock. Normally, the teeth '7 of thelower portion 54 are clear of the gear 56 (as shown in FIG. 3) but whenthe right side of the pivoted lifter element 46 (as viewed in FIG. 4) ismoved downwardly by the push button 44, these teeth are brought intoengagement with the teeth of the gear 56. This keeps the lifter element46 in its lever-lifting position until the gear 56 has been rotatedsufficiently, by the clockwork to drive the teeth 57 away from the gear,thus releasing the lifter element.

In one form of this invention, the conventional alarm clock, describedabove, is modified by providing within the clock a device whichinactivates the hammer which the sleepers hand is merely waved near theclock while the alarm is sounding. More particularly, the device is soarranged that the thrust of a hand near the clock critically alters thecontrol grid bias on a thyratron 61, thus causing the thyratron tobecome conductive (or fire) and permitting current to flow through asolenoid 62 which then acts to return the hammer to its inoperativeposition, as will be described more fully below.

The thyratron 61 has the usual anode 63, grid 64 and cathode 66 andgenerally has a cathode-heating filament 67. Usually, the current forheating the filament should be supplied at a voltage considerably lowerthan that of the usual 120 volt power supply; accordingly the filamentmay be connected to the secondary winding of a suitable transformer. Inone advantageous form of the invention I do not provide such atransformer as a separate element, but instead utilize the field coil 24of the motor as the primary winding of the transformer and connect thefilament to some turns 68 of wire wound around the same core 26. Thisreduces the cost of making the device and also saves the space whichwould be occupied by a separate transformer.

The usual alternating-current wiring to an electric outlet includes onewire that is grounded, and another wire that is hot. The circuit is suchthat the cathode 66 of the thyratron is connected to a conductor 69adapted to be connected to the hot side 71 of the A.C. power supplied tothe receptacle 23 when the plug 22 is properly inserted. This connectionextends through a switch 72, 73, or alternatively through a test switch74, 75. The anode 63 is electrically connected through the solenoid 62to a conductor 76 adapted to be in electrical contact with the groundedside 77 of the power supply.

In the particular circuit shown in the drawing, the thyratron 61 is ofthe type having a negative control characteristic, e.g., a 2D2lthyratron in Which, at the applied anode-to-cathode voltage, the bias onthe grid 64 must be a voltage more negative than the cathode to preventfiring of the thyratron. To set the grid bias at a level more negativethan the firing voltage there is a DO supply and a voltage-dividingcircuit. This circuit comprises a rectifier 78 and a filter such ascapacitor 79 to provide DC voltage across a voltage divider comprising aresistor 81 and a potentiometer 82 in series. The grid is connected tothe movable contact 83 of the potentiometer 82 through another resistor84 which serves to limit the flow of grid current. Rectifier 78 ispolarized to provide negative voltage on the grid, and the cathode 66 ofthe thyratron is connected to the positive end of the voltage divider.The resistance of resistor 81 is made quite large as compared to thetotal resistance of potentiometer 82 and there is therefore a relativelylarge voltage drop between the contact 83 and the grounded side of thepower supply. In one form of the invention, the contact of thepotentiometer is operatively attached to a control knob 85 whichprojects from the clock housing 12 to enable the user to preset the gridbias at a value which provides the sensitivity he desires, as will beexplained more fully below.

Also electrically connected to the grid 64 is a capacitive element 86 ofsubstantial area which serves to make the instantaneous voltage on thegrid susceptible to change when the body having a large capacity toground is brought into effective proximity to the clock. Thecapacitively sensitive element 86 is advantageously in the form of aconductive plate. The effect may be understood more clearly by referenceto the capacitance 87, shown in dotted lines in FIG. 6, representing thehuman bodyto-ground capacitance. When this body capacitance iseffectively coupled to the capacitively sensitive element 86, as when aperson puts his hand near that element, there is established an AC.conductive path to ground which draws a signal current from the hot"side of the power supply. This introduces an additional voltage in theform of a sinusoidal wave. At each half cycle, during the positive peak,the voltage on the control grid 64 will thus be made more positivecausing the tube to fire. Thus the control grid 64 constitutes thetrigger electrode, previously mentioned, controlling firing of thethyratron.

There are, of course, other capacitances in the thyratron circuit, suchas the small interelectrode capacitance between the cathode and thegrid, which will have an efiect on the grid bias, but these aresubstantially unaffected by the previously described changes occasionedby the approach of the body to the element 86.

The switch 72, 73, for the supply of power to the thyratron circuit, hasa fixed contact 73 and a movable contact 72 which is mounted, with thehammer 27 at the head end of the lever 29. The movable contact 72 issupported on the lever 29 by an electrically insulating member 87. Oneend 88 of the lifter element 46 is mechanically connected to the core 89of solenoid 62 through a stifl? safety spring 91. The switch contacts 72and 73 are preferably so positioned that they are brought together,during the previously described downward movement of the hammer 27, atthe time the alarm is to be sounded. The thyratron circuit is thereforefully activated, with the thyratron in its non-conducting condition, atabout the same time as the hammer begins to vibrate. If the awakenedsleeper now brings his hand close to element 86, the thyratron becomesconducting and the solenoid 62 is energized. This pulls down thesolenoid core 89 and the end 88 of the lifter element 46 and thus liftsthe hammer away from the field core 26 and opens the switch 72, 73. Thismovement of the lifter element causes it to be held in position by thelatching device 45 of the alarm-repeat control mechanism.

To prevent power line transients, on the anode-tocathode voltage, fromaccidentally causing the thyratron to fire when not coupled to bodycapacitance, the resistors 81 and 82 are so chosen that the D.C. gridbias is much more negative than the firing level. Thus, for a thyratronwhose firing level is minus 3 volts at the applied anodeto-cathodevoltage, I have found it advantageous to use a grid bias of minus 20volts (which may be measured at the movable contact 83). To attain alarge grid signal voltage, high enough to overcome this large grid bias,from the coupling of the circuit to body capacitance, I have found itadvantageous to employ a large value for the resistance 84. The grid isthus connected to the energized side of the power source through animpedance that is of the same order of magnitude as the impedanceresulting from the interposition of the humand hand. This gives aconsiderable AC. voltage drop from cathode to grid in the previouslydescribed A.C. circuit which runs to ground from the hot side of thepower line through resistor 84, capacitively sensitive element 86 andbody capacitance 87. In one example, the resistor 84 has a value of 20megohms, the resistor 81 has a value of 33,000 ohms and thepotentiometer 82 has a resistance of 5,000 ohms.

The possible effects of transients in accidentally causing the thyratronto fire are also minimized by the fact that the anode-to-cathode voltageis not applied until be moved to obtain increased about the same time asthe alarm is sounded, as previously described. The cathode of thethyratron is, however, already in its heated condition at this time thuseliminating the variations which occur during the warm-up period. In thepreferred form, as already described, the cathode is kept heatedcontinuously, and suitable vents for removing the hot air areadvantageously provided, as in the rear of the clock. The switchingarrangement may be altered so that the cathode heater is turned on (asby a switch controlled by the position of the alarm cam) only a shorttime before the switch 72, 73 is closed (that time being suificient,however, to thoroughly heat the cathode) and the heater is then turnedoff when the alarm cam pushes the apertured wheel at the close of thealarm period.

The reliability of the circuit is also enhanced by the fact that thethyratron is within the alternating magnetic field of the motor 16 (e.g.about 4 inch of the field core 26). This provides a constant ionizingfield for the gas Within the thyratron tube, overcoming thecharacteristic low reliability of many thyratrons in the darknessprevailing inside the clock, particularly when the room is dark. It alsomakes the thyratron less sensitive to, and substantially independent of,stray ionizing influences.

A test switch 74, 75, operable from a knob 92 projecting from thehousing 11, is provided to enable the user to adjust the sensitivity ofthe thyratron circuit to the level he desires for any particularpositions of the clock. When the test switch 74, 75 is closed, power issupplied to the thyratron circuit. The user, lying in bed near theclock, can close the switch, withdraw his hand, and then bring it closerto the clock until he hears the click resulting from the impact of thecore 89 on the base 93 of the solenoid 62 when the thyratron fires. Hecan withdraw his hand and repeat the process any number of times,hearing the click each time, since the thyratron, being connected acrossan A.C. cathode-to-anode power supply, will automatically becomenon-conducting when the hand is withdrawn, provided potentiometer 82 hasbeen set to give a non-firing grid bias. The user may find that, owingto a previous setting of the potentiometer contact, the circuit is sosensitive that his normal movements during sleep would bring him to aposition where his body would provide sufiicient capacitance to causethe thyratron to fire, when its circuit is powered, even without a waveof the hand. In such a case the user need merely adjust thepotentiometer, by means of its knob 85, to decrease the sensitivity bymoving his hand close to the clock and listening for the click. Again,the user may find that a previous potentiometer setting has made thecircuit so insensitive that his hand must almost touch the clock inorder to prdouce the click. He need merely move the potentiometer knobto increase the sensitivity and repeat the test, until the desiredsensitivity is attained, e.g. until the device is sensitive to theapproach of the hand to a point two inches from the outside of theclock. In each case, once the potentiometer has been properly set, it ispreferable to open the test switch '74, 75. However, it is unnecessaryto open the test switch during the adjusting process. The knob 92, orthe clock housing near the knob, is advantageously marked to indicate tothe user the directions in which the knob should and decreasedsensitivity, respectively. If the potentiometer knob is omitted the usercan employ the same testing method as described above, but altering theposition of the clock rather than its sensitivity to make the desiredadjustment.

It will be understood that when the parts are in the position shown inFIG. 3, the core 89 projects partially out of the solenoid 62, and thebottom of the core is spaced above the base of the solenoid.Energization of the solenoid then brings the core to its lowestposition. The stiff spring 91 acts as a shock absorber to prevent damageto the parts, particularly to the lifter element 46 and lever 29, duringthese movements.

A suitable A.C. bypass such as a rectifier 94 may be provided, inparallel with the solenoid 62, to reduce or eliminate chattering of thecore 89 in the solenoid when the device is being tested. So long as thegrid is made sufficiently positive to cause firing, the thyratron willshut ofl? on one half-cycle of the A.C. supply and restart on the nexthalf-cycle continually. The rectifier 94 serves to bypass the A.C.component of the output current of the thyratron so that the core 89 hasless tendency to move up and down in response to these variations.

As previously stated, the capacitively sensitive element 86 isadvantageously in the form of a conductive plate. In practice a squareplate, 25 square inches in area, attached to the base of the clock aninch below the clockwork, has proved to be very suitable. In thatposition there is a greater sensitivity to capacitive changes occasionedby the approach of the users hand, in that there is relatively littlecapacitive coupling between the capacitively sensitive element and theclockwork of the clock. However, good results have been obtained,particularly when the values of the resistances are chosen as indicatedabove, by using as the capacitively sensitive element a piece ofaluminum foil placed just behind the clock face 13 and flush therewith.When the face itself is of metal it may be employed as the capacitivelysensitive element. It will be appreciated that the capacitivelysensitive element 86 may be situated between, and protected by,electrical insulating elements or insulating coatings, and may belocated on the top or sides of the clock instead of, or as well as, atthe bottom. The capacitively sensitive element may also be a plateseparate from the clock, and connnected to the grid by means of aflexible conductor. Such an arrangement is, however, less preferablethan the form previously described in which the clock, with the plate,is a unitary self-contained device.

It will be understood that, in the form illustrated, the plu'g' 2 2 mustbe inserted in the correct way into the receptacle 23 so that thethyratron anode 63 is electrically connected to the grounded side of thepower line. To facilitate this, the plug is advantageously suitablymarked, as by making the prongs of different sizes or placingappropriate indicia opposite one prong or the other. In any event, theuser can make a simple preliminary test to determine whether the plughas been inserted correctly. One such test involves closing the testswitch 74, 75, setting the potentiometer knob 92 by hand until the clickis heard, removing the hand and then bringing the hand close to theclock. If neither the removal of the hand nor its reapproach to theclock then have any effect, the plug should be reversed and the knob 92reset to the desired sensitivity.

It will be apparent that various embodiments of. the invention may bedevised by those skilled in the art, utilizing the novel features in thedevice specifically described above. Consequently, the invention shouldbe construed broadly, in accordance with its full spirit and scope.

What is claimed is:

1. An electric clock having alarm means and having an alternatingcurrent motor, connections for said motor to an alternating currentsupply line that characteristically has a hot side and a grounded side,normally passive means including a control electrode responsive toactivating signals for deactivating said alarm rneans, and meansincluding an impedance connected in a circuit between said controlelectrode and said hot side of the alternating supply line via one ofsaid connections of said motor for developing activating signals forsaid normally passive means, said last-named means including acapacitive element physically connected to said clock and coupled tosaid control electrode for coupling said impedance to the grounded sideof the alternating current supply line 7 via human body capacitance uponapproach of a human hand to the clock.

2. An alarm clock as in claim 1 wherein said clock has a casing to whichsaid capacitive element is secured and wherein said means including saidcapacitive element for developing said activating signals is renderedoperative by the approach of a human hand to a zone in the atmospherearound said clock and casing about two inches outside said casing.

3. An electric alarm clock as in claim 1 including a normally openswitch closable approximately at the start of alarm operation forrendering operable the coupled capacitive element and normally passivemeans, whereby a signal on said trigger electrode substantially earlierthan the start of alarm operation will be ineffective to bring thetime-controlled alarm to its inactivated condition.

4. An electric alarm clock as in claim 3 and including manually operableswitch means operable independently of the alarm for rendering operablethe coupled capacitive element and normally passive means, and manuallyoperable means for adjusting the sensitivity of the coupled capacitiveelement and normally passive means when in said operable conditionwhereby the user can test the sensitivity of the clock to thealarm-inactivating effect of human body capacity without sounding thealarm.

5. An electric alarm clock as in claim 1 and including solenoid havingan alarm-inactivating core and an alternating current bypass in parallelwit-h the solenoid to reduce chattering of the core in the solenoid whenthe alarm-inactivating means is being tested.

6. An alarm clock as set forth in claim 1, said trigger electrode havinga predetermined firing level and said responsive means including meansproviding an antifiring bias on said trigger electrode greatly in excessof said firing level.

7. An alarm clock as set forth'in claim 1, said trigger electrode beingconnected to the energized side of said power source through animpedance that is of the same order of magnitude as that of thecapacitive element when in operative cooperation with the human hand.

References Cited by the Examiner UNITED STATES PATENTS 1/1936 Ostermeieret al. 328-5 3/1963 Atkins et al. 5050

1. AN ELECTRIC CLOCK HAVING ALARM MEANS AND HAVING AN ALTERNATINGCURRENT MOTOR, CONNECTIONS FOR SAID MOTOR TO AN ALTERNATING CURRENTSUPPLY LINE THAT CHARACTERISTICALLY HAS A "HOT" SIDE AND A GROUNDEDSIDE, NORMALLY PASSIVE MEANS INCLUDING A CONTROL ELECTRODE RESPONSIVE TOACTIVATING SIGNALS FOR DEACTIVATING SAID ALARM MEANS, AND MEANSINCLUDING AN IMPEDANCE CONNECTED IN A CIRCUIT BETWEEN SAID CONTROLELECTRODE AND SAID "HOT" SIDE OF THE ALTERNATING SUPPLY LINE VIA ONE OFSAID CONNECTIONS OF SAID MOTOR FOR DEVELOPING ACTIVATING SIGNALS FORSAID NORMALLY PASSIVE MEANS, SAID LAST-NAMED MEANS INCLUDING ACAPACITIVE ELEMENT PHYSICALLY CONNECTED TO SAID CLOCK AND COUPLED TOSAID CONTROL ELECTRODE FOR COUPLING SAID IMPEDANCE TO THE GROUNDED SIDEOF THE ALTERNATING CURRENT SUPPLY LINE VIA HUMAN BODY CAPACITANCE UPONAPPROACH OF A HUMAN HAND TO THE CLOCK.